Apparatus for transmitting music by radio



Oct. 30, 1934. G. W, WATSON 1,978,828

APPARATUS FOR TRANSMITTING MUSIC BY RADIO Filed June 2. 1951 2 sheets-sheet 1 mh. m. n nhl 6 ,Www .m ww me. mw. amr

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Oct. 30, 1934. G, W. WATSON APFRIUS FOR TRANSMITTING MUSIC BY RADIO 2 Sheets-Sheet Filed Jung 2, 1951 R O T N E V m me.

ATTORNEYS Patented oci. 3o, 1934 APPARATUS Fon TBANSMITTING Music BY RADIO Glenn W. Watson, Detroit, Mich., assignor to International Business AMachin es Corporation,

New York, N. Y., a corporation of New York Application June 2, 1931, Serial No. 541,634

' 5 claims. (ci. 84-174) The present invention pertains to a novel system of' transmitting musical compositions by radio impulses. The system is here exemplified by means of two pianos at the sending and re- 5 ceiving stations respectively, in conjunction with radio transmission apparatus whereby a selection played on the sending piano is mechanically reproduced on the receiving piano.

In one embodiment, the invention operates on the principle of synchronized contact devices as described 4in my co-pending application, Serial No. 529,436, Iiled` April 11, 1931, now Patent No. 1,927,077, dated September 19, 1933. striking of a key on the sending instrument causes the closing of the transmission circuit,

whereupon an impulse is picked up at the receiving station and caused to operate the corresponding key of the instrument there.

Inasmuch as the impulses are of very short duration, the invention provides means for prolonging the striking ofthe keys so that the notes will not be sounded too sharply. This device comprises rotary switches operable on the sending of an impulse and governed by means 2:5v which permit a prolonged closed interval thereof.

The invention modifying thetone, consisting of a. variable resistance at the receiving station. The disks carry contacts associated with various points along the resistance, and a switch is provided at the sending station for selectively making any of these contacts effective on engagement thereof by the rotary contacts associated with the disks. When a circuit is `completed through any such contact, a portion of the cut out, and the force with which'the note is played at the receiving instrument i`s increased.

'I'he invention further comprises a similar means operable from the pedals of the sending instrument and adapted to operate corresponding pedals at the receiving instrument.

The invention is fully described by way of example in the following description and in the accompanying drawings, in which- Figure 1 is a diagrammatic view of the transmitting and receiving apparatus;

Fig. 2 is a detail elevation, partly in section, of the receiving apparatus;

Fig. 3 is a section on the line 3 3 of Figure 2;

Fig. 4 is a sectional perspective view of a detail of the sending mechanism;

Fig. 5 is a similar detail of the receiving apparatus;

. Fig. 6 is an elevation corresponding t0 Fg- Thel further embodies means forl resistance is Fig. 7 is a detail section of a modified form of receiving apparatus;

Fig. 8 is a diagrammatic view of a modified system; and

Fig. 9 is a section approximately on the line 60 9 9 of Figure 8.

Reference to these views will now be made by use of like characters which are employed to designate corresponding parts throughout.

'Ihe transmitting apparatus includes a con- 65 ventional or modified piano having a series of pivoted key bars 1. A contact disk 2 carries a series ofl spaced contacts 3 corresponding respectively to the various notes sounded by striking the bars 1. The contacts are engaged in rather rapid succession by a rotary contact arm 4 driven by a. motor 5, spring or electric which is in synchronismwith a similar device at the receiving station as will presently appear. Obviously, the disk rather than the arm may rotate if more convenient. i.

Each; of the keys 1 carries a) contact 6 normally spaced from a contact 7 therebeneath and adapted to engage the lower contact when the key is struck. The contacts 7 are joined by conductors 8 respectively to the contacts 3 on the disk 2. The contacts 6 are joined by branch conductors 9 to a common conductor 10 leading to one side of a battery 11. The other side of the battery is joined by a conductor 12 to one of the input terminals of a radio transmitter 13,

,the other input terminal of the transmitter being joined by a conductor 14 to the rotary arm 4. One of the outputv terminals of 'the-transmitter is grounded at 15, and the other output terminal is joined'by a conductor 16 to an antenna 17. When a key 1 is struck and the arm 4 engages the corresponding contact 3, a circuit is completed from the battery 11 through conductor 10, conductor 9 leading to the mutually contacting members 6 and: 7 through conductor 8 to the corresponding contact 3, arm 4, conductor 14, transmitter 13 and conductor 12 to the other side of -the battery. This circuit energizes the transmitter, whereupon an impulse is sent out i'rom'the antenna 17. The arm 4 is timed to make one revolution in no more than theA time during which a pair of contacts 6, 7 are in mutual contact. 105

The receiving apparatus also includes a contact disk 18 having contacts 19 corresponding to the contacts 3 in succession and angular relation.k The members 19 are also engaged successively by a rotary contact arm 20 driven by 110 23 which turns y l velocity as the arm 20. Contact disks 24 corresponding in number to the contacts 19 are loosely 20 producing mechanism l further provided with a cylinder 35 thereby,

2 a suitable motor 21-which is synchronized with the motor 5.

A shaft 22 is operatively connected to the motor 21, as shown in Figure 2, by suitable gearing the shaft at the same angular mounted on the shaft and having frictional driving relation therewith by means of spring iin- 10 gers 25 engaging the disks and extending from collars 26 fixed to the shaft. The conductingportion of each disk comprises two concentric circular strips 27 joinedby a radial piece 28 as shown in Figure 3. This conductor takes cur- 15 rent from a'flxed brush 29 which is connected to a suitable source of current by means which will presently be described. The larger circle 27 has an insulated gap 30 adapted to receive another brush 31 from which current is led off to sound as will presently appear.

Adjacent each disk 24 is a solenoid 32 containing a plunger 33. The plunger acts as a detent for the disk by cooperating with a tooth 34 projecting from the latter. Each solenoid is in which is received a piston 36 connected to the plunger 33 by a rod 37. Behind-the-piston is a spring 38 moving thek plunger outwardly orto the position where it engages the tooth 34. At the other 30 side of the piston, the cylinder has a small port 39, and this construction constitutes a dash pot retarding the projection of the plunger under the action ofthe spring. Obviously, when the' solenoid is energized, the plunger is attracted turn by reason of its frictional connection with the shaft 22. The solenoids 32 each have one terminal joined by conductors 40 to the contacts 19 and the remaining terminals connected alter- 40 nately to common conductors 41 and 42 as shown more clearly in Figure 1. y

'I'he receiving circuitincludes a receiver 43 having one of its input terminals grounded at 44 and its other' input terminal connected to an 45 antenna 45 adapted to receive the impulse sent out from the antenna 17 in the usual manner.

' Also embodied in the receiving circuit is a series of mercury vapor tubes 46, here represented by two such tubes. One of the output terminals of the receiver 43 is connected by branch conductors 47 to the grids 48 of the tubes, and the other output terminal is connected by branch conductors 49 to the filaments 50 of the tubes. The conductors 49 arefconnected to one side of a battery 51, and the other side of the Abattery is joined by a common-conductor 52 to the rotary arm 20. 0n energization of one ofthe tubes 46 by reception of an impulse, a circuit is completed from the battery 51 to conductor 52, arm 20,

through the contact 19 engaged by the arm at that instance, through conductor 40 to the corresponding' solenoid 32, through conductor 41 or 42 to the corresponding tube, and thence to the other side of the battery 51. The plunger 33 of the energized solenoid is withdrawn from the adjacent disk 24,` as already described, an

the disk commences to rotate.

-At the receiving station is also provided a piano having the usual keys 53. Beneath each 70, key is provided a solenoid 54 having'a core 55 connected to the corresponding key by a cord or exible spring steel 56. A shaft 57 extends transversely of the cords and carries a roller 58. engageable by the cords whenI the latter are drawn by movement of the cores 55 0n energizaand the contact disk is permitted to' tion of the solenoids 54. Like terminals of the solenoids 54 are connected by conductors 59 to the respective brushes 31. The remaining terminals are branched into a line 60 connected to one side of a secondary battery 61. A conductor 62 leads from the other side of the battery and is branched as at 63 to the corresponding brushes 29. Thus, when a contact disk 24A is set in motion in response to the striking of a key 1 as already described, it completes a circuit through the battery 61 and the corresponding solenoid 54. The consequent attraction of the core 55 draws the cord 56 into engagement with the ribbon roller 58, whereupon the key 53 connected thereto is drawn downwardly and the corresponding note is sounded on the piano at the receiving station.

At suitable intervals on the disk 2 are mounted series of tone-'modifying contacts 64. As an example, three such contacts are shown in each series. These members are connected Arespectively to concentric conductors 65 which in turn are joined to fixed contacts 66 mounted on the transmitting piano. A pivoted contact 67 is adapted to-engage any one of the contacts 66 and is operated by the knee of the player. The contact 67 is joined Yby a conductor 68 into the line 10 so that an impulse is sent out when the arm 4 engages the contact or lcontacts 64 connected to the contact 66 engaged by the member 67.

'I'he disk 18 carries similar sets of contacts 69 l corresponding in number and spacing to the contacts 64. The members 69 .are also joined to concentric conductors 70.

For each contact 64 in a'set, there is provided a rotary contact disk 7l similar to the members 24 and also mounted on the shaft 22 in the same manner as the members 24. The members 71 are adapted to be held by plungers 72 actuated by solenoids 73 which have like terminals branched as at 74 alternately into the lines 41 and 42. The remaining terminals of the solenoids are joined by conductors 75 respectively tothe contacts 69 on the disk 18.

A resistance 76 is inserted in the line 62 and is adapted to be cut out partly or entirely by operation of the contact disks 71 as will presently appear. The brushes 77 associated with the disks are joined to various points on the resistance 76 by conductors 78, one of them being connected to the end of the resistance. A line 79 extends from the other end of the resistance and is branched at 80 to the permanently engaged' brushes 81 associated with the contact disks.

The movable contact 67 is actuated simultaneously with the striking of a key and brought into engagement with a particular contact 66 for the desired tone modication. An impulse for this modification, depending on engagement of the arm 4 with the corresponding contact 64 is sent out immediately after the note impulse because of the high speed of the arm 4 and the provision of several sets of contacts 64 on the disk 2. When the' modifying impulse is sent out, the arm 20 is in engagement with the corresponding contact 69 on the disk 18 because of the synchronized relation of the arms 4 and 20. At this time, a circuit is completed through the solenoid 73 corresponding to the engaged-,contact 69, and the adjacent disk 71 is released and permitted to rotate to.' make contact with its brush 77. The current` 'emanating from the battery 61 for operating the corresponding solenoids 54 as already described, instead of passing through the entire resistance 76, is diverted therefrom through the line 79 and a branch 80 -to the brush 81A of the moving disk 71 and then returned to an intermediate point of the resistance 76 or to the output end thereof through the brush 77 and conductor 78 of the moving disk 71, whereby the portion or all of the resistance 76 is cut out. The current having returned from the moving disk 71 to the line 62 at the output side of the resistance 76, passes through the disk 24 corresponding to the note which was struck and completes the -circuit through the corresponding solenoid 54 in the manner already described. Thev strength of the current passing through the solenoid 54 is determined by the amount of resistance 76 which has been cut out and in turn determines the force with which the core 55 is attracted and with which the connected key 53 is struck. This modification of the tone is similar to that produced by different kinds of touches on the keys of a piano, such as a sharp impact or a more prolonged impact on a key, and governs the du-y ration of. the sounding of the note at the receiving instrument. These eiects would not ordinarily be reproduced in the receiving instrument, since the note impulses sent from the transmitter merely closes a circuit in the receiving instrument, but in the present instance are realized by operation of the movable contact 67.

The sending instrument, as shown in Figure 4, has the usual loud and soft pedals 82 and 83 respectively. 'Ihe former when actuated removes a transverse damper 84 from contact with the piano wires 85, and the latter when! actuated shortens the stroke of the hammers 86 through the action of a rest bar 87, in the usual manner. Beneath the pedals 82 and 83 are xed contacts 88 engageable on depression of the pedals. lThese'conta'cts are joined by conductors 89 to contacts 90 on the disk 2 and engageable by the arm 4. The pedals are further branched as at 91 into the common conductor 10. When a pedal is depressed until engagement` with lits contact 88 and the corresponding contact 90 is engaged by the arm 4, a circuit is established through the transmitter 13 and sends out an impulse.

The receiving apparatus includes a pair of rotary contact disks 92 similar to the members 24 and 71 and mounted on the shaft 22 in the same manner. Associated with each of these disks is a solenoid `93 having a plunger 94 serving as a detent for the disk. Contacts 95 corresponding to the contacts 90 are mounted on the disk 18 and are joined by conductors 96 to like terminals of the solenoids 94. The remaining terminals of the solenoids are joined by conductors 97 into the lines 41 and 42. 'I'he contacts 90 and 95 occupy like positions on the disks 2 and 18 respectively. When an impulse depending on a contact 90 is received, the arm 20 engages vlthe corresponding contact 95, whereby the circuit is completed through the arm 20 and corresponding contact, solenoid 93,

tube 46 and battery 5l. The solenoid thus energized causes the release of the adjacent disk 92 so that the latter commences to rotate. The disengageable brushes 98 of these disks are connected to like terminals of solenoids 99, the remaining terminals of which are branched into a line 100 connected into the conductor 60 at a point between the battery lhand the nearest 3 solenoid 54. The permanentlyl engaged contacts 101 of the disks are joined by lines 102 to the battery 61.

The reproducingA piano, as shown in Figure 5, also has a damper 103 normally engaging the piano wires 104 and operable by linkage 105. The stroke of the hammers 106 is also variable by means of a rest bar 107 which is operable through a rod 108. The plungers 109 of the solenoids 99 are connected respectively to the members and 108.

Whena disk 92 is set into motion onoperation of a pedal 82 or 83 as described, it takes current from the battery 61, delivers it to the corresponding solenoid 99 and returns it to the battery through conductor 100. 'Ihe core 109 of the energized solenoidis thus attracted and, being connected to a member 105 or 108 actuates this member and makes an adjustment in the tone of the receiving piano corresponding to the adjustment effected by actuation of the pedal 82 or 83.

The several solenoid plungers 33, 72 and 94 are returned by their respective springs in a retarded manner through the action of the dash pots 35, 39 associated therewith. The retarded return of the plungers is provided for two reasons. First. the rotary contact disks may not start to turn immediately they are released by their respective plungers, owing -to 105 the lag therein to their frictional connection with the shaft 22. Consequently, it is necessary that the plungers shall not return to locking' position before the disks start, and the retardation of the plungers'accomplishes this purpose. 110 Secondly, the arm 20 and hence the rotary contacts turn at a high rate of speed, and hence the flow of current through the rotary contacts and solenoids 54 is of very short duration. This would ordinarily result in a too rapid impact of the piano keys 53. The dash pots are constructed so that the plungers will not return to locking position until the rotary contacts have made at least one and a fraction revolutions, whereupon the iiow of current through the solenoids 54 is prolonged. The armature of the solenoid is therefore held back so that in case a repeated iiow of impulses occurs, in playing a long note, one with each revolution of the arm 20, the contact disk continues to revolve without being locked at each revolutionin the lag in. terval of thedisk in approaching the plunger, through the return action of the plunger. Thus the piano key is held down Without return until the` impulses cease. the minute breaks in the current to the key solenoid 54 is not an impediment to the continued vibration of the piano string. This is due to the fact that standard piano construction permits a small rise and return of the key from its lowermost depressed position Without dampening the piano string. When the contacts 54 are nally stopped, the disengag'eable brushes associated therewith are in the insulated gaps 30, as shown in Figure 3, so that no current flows therethrough. l Y

If the energization of a solenoid 54 were con caved with the engagement of any one contact 19 by the arm 20, such instantaneous action of the solenoids would either produce very sharp and abrupt sounds or no sounds at all. 'Ihis diiculty is overcome by the action of the rotary contacts 24 which, upon instantaneous release by the armatures 33, produce a prolonged ow of current through the solenoids 54. 155

The gap 30 is so small that 130 the board and by a single impulse, depending on which contact 19 of the receiving contact disk is engaged by the revolving arm 20. Each tube is operative on only a limited number of alternate solenoids 32, so that the lag in a tube in circuit with a given segment 19 will not pass current through the next adjacent` segment, since the latter segment at the instance of impulse was not engaged by the arm 20 and therefore didnot provide a closed circuit-which is necessary for ionization of the corresponding tube.

It will be noticed that the receiving contacts 19 are of greater length circumferentially than the sending contacts 3. In fact the latter are made as short as possible in order that the transmitted impulse may be instantaneous. The longer receiving contacts 19, however, hold the receiving circuit closed for an interval suicient to enable the energization of the solenoids 3,2, 73 and 93 and release of the corresponding plungers, as well as to allow for slight inaccuracies in the synchronism of the transmitting and receiving arms 4 and 20 respectively. The comparatively short space between adjacent contacts 19 is suflicient to break the receiving circuit andde-ionize the tubes 46, despite any lag in the tubes, since a given tube is notl in circuit with two adjacent contacts 19, as stated above.

The modification shown in Figure 7. illustrates a detail of an automatic player piano or pneumatic piano used as the receiving instrument. This device embodies a tracker board 110 having air passages 111 over which a perforated 'roll is ordinarilymoved. Pipes 112 corresponding to the various notes are connected to bellows 113 in which a suction is constantly produced through pipes 114. Over each bellows is pivotally mounted a'hammer 115 adapted to' strike ,a piano wire 116. A rod 117 connects the'top of each bellows to the corresponding hammer 115, so that the hammer strikes its wire when the bellows expands. This construction is substituted for the keyboard construction shown in Figure 1, and the solenoids 54 of Figure 1 are replaced by solenoids 118 having plungers 119 adapted to extend into-the respective passages 111 and normally obstruct the same. When a solenoid 118 is energized by the transmission and reception of. an impulse in a manner already described, the plunger 119 thereof -is withdrawn from the corresponding air passage 111', opening the latter to the atmosphere and causing the corresponding bellows 113 to expand, whereupon the corresponding wire 116 is struck.

In the modification shown in Figures 8 and 9, the sending piano and contact disk are replaced by a motor board 120 synchronously connected by gearing 121 with the transmitting disk 18 similar to that shown in Figure 1 and having like appurtenances. A record 122 is placed upon is formed with a spiral track 123 having bumps or depressions 124 at certain predetermined intervals. A reproducer 125 of the electrical contact type has a needle 126 adapted to ride in the groove 123. This reproducer occupies the position of the receiver 43 in Figure 1 and, like thereceiver, completes a circuit through mercury vapor tubes 46', resulting in the actuation of rotary contact disks 24. as previously described.

The bumps 124 on the record 122 represent notes to be played and are so spaced apart as to be engaged by the needle 126 and close the contacts 127 in the reproducer 125 when the corresponding note contacts on the disk 18' are engaged by the rotary arm 60' thereof.

It will be noted that due to the speed of the revolving arm 20, a chord or chords played on the broadcasting piano will be received one note behind the other with such rapid sequence as to sound like a solid chord. This is due to the slowness of the human ear to detect the slight time separation of notes. Due to this characteristic, any note on a prepared record may be treated or modified separately, although it is in a chord for all practical purposes, and may thus be caused to stand I,out louder than the notes played immediately before or after in the same apparent chord, or to produce what is knownin musical terms as a solo note. In other means of reproducing music, as from paper rolls or wax records, it is impossible to modify a selected note of a chord, inasmuch as all the notes of a chord occur simultaneously on the roll or record. n,

In the use of the knee pedal 67, the engagement of a contact 66 for a given volume requires passage through the preceding contacts 66 or in other words the lower volumes. Thus, a crescendo or dimutto of soundeiected by the pedal 67 is 'gradual/ rather than in the nature of a sudden break from normal to loud or loud tonormal.

Although specific embodiments of the invention have been illustrated and described, it will be understood that various alterations vin the details of construction may be made without departing from the scope of theinvention, as indicated by the appended claims.

What I claim is:- 1. In combination with a system for the transmission of musical sounds including transmitting and receiving disks, corresponding contacts on said disks representing musical notes, a common contact associated with each disk engageable with the contacts thereon and movable relatively thereto, synchronized means moving said common contacts relatively -to the respective disks, sending keys corresponding individually to the contacts on said sending disk, and a transmission circuit adapted to operate on actuation of a key and on engagement of said note contacts by the corresponding common contacts; of a musical instrument, operating means for said instrument electrically connected to the contacts and receiving disks, corresponding contacts on said disks representing musical notes, a common contact associated with each disk engageable withthe contacts thereon and movable relativeily thereto,` synchronized means moving said common cntacts relatively to the respective disks, sending keys corresponding individually 4-to the contacts on said sending disk, and a transmission circuit adapted to operate Aon actuation of a key and on engagement of said note contacts by the corresponding common contacts, of a musical instrument, operating means for said instrument electrically connected to the contacts of said receiving disk and to the common contact thereof and operable on closing of a circuit through said receiving disk vand its common contact, tone-modifying contacts on said disks in like relative positions and engageable by said common contacts to operate the transmission circuit, tone-modifying means at said musical instrument, rotary switches associated with said tone-modifying means and said musical instrument operative on engagement of said tone-modifying contacts by said common contacts, and mechanical switches at said sending disk for selectively bringing said tone-modifying contacts into the transmission circuit.

3. In combination with a system for the transmission of musical sounds including transmitting and receiving disks, corresponding contacts on said disks representing musical notes, a common contact associated with each disk engageable with the contacts thereon and movable relatively thereto, synchronized means moving said common contacts relatively, to lthe respective disks, sending keys ,corresponding individually to the contacts on said sending disk, and a transmission circuit adapted to operate on actuation of a key and on engagement of said note contacts by the corresponding common contacts; of a musical instrument, a solenoid adjacent each key of said instrument and having a movable plunger, cords connecting said plungers to the corresponding keys, a'driven roller spaced slightly from said cords, said solenoids being electrically connected to the note contacts of said receiving disk and the common contact of said disk and adapted to draw said cords into lengagement with said roller on the closing of a circuit through said receiving disk and its common contact. f

4. In combination with a system for the transmission and translation oi electrical impulses and including a transmitting member and areceiving member each provided with contacts each corresponding to a certain impulse and a contact member associated with each of said members and adaptedto successively engage said contacts thereof, sending keys each corresponding to a contact on said sending member, 'a transmission circuit adapted to transmit an impulse upon actuation of a sending key and upon engagement of said contact member of said transmitting member with the contact thereon corresponding with said actuated keyj of a separate driving means for each of said members separately energized by current iiow independent of and uncontrolled by said receiving and transmitting members, one of said driving means being synchronized `with the other, a musical instrument having keys for playing the same, and .means for operating each of said keys including an electrically operated device and a switch device, each electrically connected to a contact of said receiving member and to said contact member thereof to close said circuit upon contact of said contact member with said contact on said receiving member and operate a playing key of said musical instrument.

5. In a system as characterized in claim 4 and wherein said driving means comprises synchronized motors and wherein said means for operating said keys of said musical instrument'includes a switch and an electric circuit within mlsv which each of said keys is connected and the Y corresponding contacts on said receiving member, an electro-magnet in said circuit for holding and releasing said being adapted to release said switches upon the closing of said circuit through said receiving member and its contact member, a circuit for each of said keys of said instrument, and an electrically operated device in each circuit for each key and energized upon depression of each key and the closing of its circuit thereby.

GLENN W. WATSON.

switches, said electro-magnets 

